refactor(chat): simplify history logic (#6946)

## Problem
History logic cleanup

## Solution
- History does not need to be in triggerPayload
- ChatHistory does not need tools
- We don't need to create and maintain a separate newUserMessage object

---

- Treat all work as PUBLIC. Private `feature/x` branches will not be
squash-merged at release time.
- Your code changes must meet the guidelines in
[CONTRIBUTING.md](https://github.com/aws/aws-toolkit-vscode/blob/master/CONTRIBUTING.md#guidelines).
- License: I confirm that my contribution is made under the terms of the
Apache 2.0 license.

Author: ctlai95

packages/core/src/codewhispererChat/controllers/chat/chatRequest/converter.ts

@@ -175,7 +175,6 @@ export function triggerPayloadToChatRequest(triggerPayload: TriggerPayload): { c
             },
             chatTriggerType,
             customizationArn: customizationArn,
-            history: triggerPayload.chatHistory,
         },
     }
 }

packages/core/src/codewhispererChat/controllers/chat/controller.ts

@@ -82,7 +82,6 @@ import {
     createSavedPromptCommandId,
     aditionalContentNameLimit,
     additionalContentInnerContextLimit,
-    tools,
     workspaceChunkMaxSize,
     defaultContextLengths,
 } from '../../constants'
@@ -1355,24 +1354,15 @@ export class ChatController {
         triggerPayload.contextLengths.userInputContextLength = triggerPayload.message.length
         triggerPayload.contextLengths.focusFileContextLength = triggerPayload.fileText.length
 
+        const request = triggerPayloadToChatRequest(triggerPayload)
+
         const chatHistory = this.chatHistoryStorage.getTabHistory(tabID)
-        const newUserMessage = {
-            userInputMessage: {
-                content: triggerPayload.message,
-                userIntent: triggerPayload.userIntent,
-                ...(triggerPayload.origin && { origin: triggerPayload.origin }),
-                userInputMessageContext: {
-                    tools: tools,
-                    ...(triggerPayload.toolResults && { toolResults: triggerPayload.toolResults }),
-                },
-            },
+        const currentMessage = request.conversationState.currentMessage
+        if (currentMessage) {
+            chatHistory.fixHistory(currentMessage)
         }
-        const fixedHistoryMessage = chatHistory.fixHistory(newUserMessage)
-        if (fixedHistoryMessage.userInputMessage?.userInputMessageContext) {
-            triggerPayload.toolResults = fixedHistoryMessage.userInputMessage.userInputMessageContext.toolResults
-        }
-        triggerPayload.chatHistory = chatHistory.getHistory()
-        const request = triggerPayloadToChatRequest(triggerPayload)
+        request.conversationState.history = chatHistory.getHistory()
+
         const conversationId = chatHistory.getConversationId() || randomUUID()
         chatHistory.setConversationId(conversationId)
         request.conversationState.conversationId = conversationId
@@ -1426,8 +1416,8 @@ export class ChatController {
             }
             this.telemetryHelper.recordEnterFocusConversation(triggerEvent.tabID)
             this.telemetryHelper.recordStartConversation(triggerEvent, triggerPayload)
-            if (request.conversationState.currentMessage) {
-                chatHistory.appendUserMessage(request.conversationState.currentMessage)
+            if (currentMessage) {
+                chatHistory.appendUserMessage(currentMessage)
             }
 
             getLogger().info(

packages/core/src/codewhispererChat/controllers/chat/model.ts

@@ -6,7 +6,6 @@
 import * as vscode from 'vscode'
 import {
     AdditionalContentEntry,
-    ChatMessage,
     Origin,
     RelevantTextDocument,
     ToolResult,
@@ -203,7 +202,6 @@ export interface TriggerPayload {
     traceId?: string
     contextLengths: ContextLengths
     workspaceRulesCount?: number
-    chatHistory?: ChatMessage[]
     toolResults?: ToolResult[]
     origin?: Origin
 }

packages/core/src/codewhispererChat/storages/chatHistory.ts

@@ -2,10 +2,9 @@
  * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
  * SPDX-License-Identifier: Apache-2.0
  */
-import { ChatMessage, Tool, ToolResult, ToolResultStatus, ToolUse } from '@amzn/codewhisperer-streaming'
+import { ChatMessage, ToolResult, ToolResultStatus, ToolUse } from '@amzn/codewhisperer-streaming'
 import { randomUUID } from '../../shared/crypto'
 import { getLogger } from '../../shared/logger/logger'
-import { tools } from '../constants'
 
 // Maximum number of messages to keep in history
 const MaxConversationHistoryLength = 100
@@ -20,12 +19,10 @@ export class ChatHistoryManager {
     private history: ChatMessage[] = []
     private logger = getLogger()
     private lastUserMessage?: ChatMessage
-    private tools: Tool[] = []
 
     constructor(tabId?: string) {
         this.conversationId = randomUUID()
         this.tabId = tabId ?? randomUUID()
-        this.tools = tools
     }
 
     /**
@@ -97,10 +94,10 @@ export class ChatHistoryManager {
      * 4. If the last message is from the assistant and it contains tool uses, and a next user
      *    message is set without tool results, then the user message will have cancelled tool results.
      */
-    public fixHistory(newUserMessage: ChatMessage): ChatMessage {
+    public fixHistory(newUserMessage: ChatMessage): void {
         this.trimConversationHistory()
         this.ensureLastMessageFromAssistant()
-        return this.handleToolUses(newUserMessage)
+        this.ensureCurrentMessageIsValid(newUserMessage)
     }
 
     private trimConversationHistory(): void {
@@ -145,42 +142,27 @@ export class ChatHistoryManager {
         }
     }
 
-    private handleToolUses(newUserMessage: ChatMessage): ChatMessage {
+    private ensureCurrentMessageIsValid(newUserMessage: ChatMessage): void {
         const lastHistoryMessage = this.history[this.history.length - 1]
-        if (!lastHistoryMessage || !lastHistoryMessage.assistantResponseMessage || !newUserMessage) {
-            return newUserMessage
-        }
-
-        const toolUses = lastHistoryMessage.assistantResponseMessage.toolUses
-        if (!toolUses || toolUses.length === 0) {
-            return newUserMessage
-        }
-
-        return this.addToolResultsToUserMessage(newUserMessage, toolUses)
-    }
-
-    private addToolResultsToUserMessage(newUserMessage: ChatMessage, toolUses: ToolUse[]): ChatMessage {
-        if (!newUserMessage.userInputMessage) {
-            return newUserMessage
+        if (!lastHistoryMessage) {
+            return
         }
 
-        const toolResults = this.createToolResults(toolUses)
+        if (lastHistoryMessage.assistantResponseMessage?.toolUses?.length) {
+            const toolResults = newUserMessage.userInputMessage?.userInputMessageContext?.toolResults
+            if (!toolResults || toolResults.length === 0) {
+                const abandonedToolResults = this.createAbandonedToolResults(
+                    lastHistoryMessage.assistantResponseMessage.toolUses
+                )
 
-        if (newUserMessage.userInputMessage.userInputMessageContext) {
-            newUserMessage.userInputMessage.userInputMessageContext.toolResults = toolResults
-        } else {
-            newUserMessage.userInputMessage.userInputMessageContext = {
-                shellState: undefined,
-                envState: undefined,
-                toolResults: toolResults,
-                tools: this.tools.length === 0 ? undefined : [...this.tools],
+                if (newUserMessage.userInputMessage?.userInputMessageContext) {
+                    newUserMessage.userInputMessage.userInputMessageContext.toolResults = abandonedToolResults
+                }
             }
         }
-
-        return newUserMessage
     }
 
-    private createToolResults(toolUses: ToolUse[]): ToolResult[] {
+    private createAbandonedToolResults(toolUses: ToolUse[]): ToolResult[] {
         return toolUses.map((toolUse) => ({
             toolUseId: toolUse.toolUseId,
             content: [